The issue appears to be with the Syrian safe zones, which ironically were a long-time pet project of the Turkish government, with the Turkish delegation apparently refusing to agree to a deal on implementation of the safe zones, insisting they need more time.

It is unclear what Turkey’s specific objection was, if any, to a plan which would’ve seen Russia, Turkey, and Iran each deploy military police to the borders of the safe zones to prevent any incursions. The deal will be brought up again at a meeting in early August.

The four safe zones established don’t appear to intersect with Turkey’s military possessions inside northern Syria at any rate, nor are they in the way of an apparently imminent war between Turkey and north Syria’s Kurdish YPG forces, and Turkish officials gave no indication what the problem was, apart from needing more time to “consider” the matter.